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Diffstat (limited to 'html-test/src/SpuriousSuperclassConstraints.hs')
-rw-r--r-- | html-test/src/SpuriousSuperclassConstraints.hs | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/html-test/src/SpuriousSuperclassConstraints.hs b/html-test/src/SpuriousSuperclassConstraints.hs new file mode 100644 index 00000000..d9e43e1c --- /dev/null +++ b/html-test/src/SpuriousSuperclassConstraints.hs @@ -0,0 +1,30 @@ +{-# LANGUAGE EmptyDataDecls, KindSignatures #-} +-- | +-- What is tested here: +-- +-- Due to a change in GHC 7.6.1 we had a bug that superclass contraints were +-- included in the instances list. Edward K. repported it here: +-- +-- <http://www.haskell.org/pipermail/haskell-cafe/2012-September/103600.html> +-- +-- And here is the corresponding theard on glasgow-haskell-users: +-- +-- <http://www.haskell.org/pipermail/glasgow-haskell-users/2012-September/022914.html> +-- +-- It has been fixed in: +-- +-- > 6ccf78e15a525282fef61bc4f58a279aa9c21771 +-- > Fix spurious superclass constraints bug. +-- +module SpuriousSuperclassConstraints where + +import Control.Applicative + +data SomeType (f :: * -> *) a + +instance Functor (SomeType f) where + fmap = undefined + +instance Applicative f => Applicative (SomeType f) where + pure = undefined + (<*>) = undefined |